Catalytic metal additive concentrate and method of making and using

ABSTRACT

Delivery of metallic combustion catalysts to internal combustion engines and other combustion devices is improved by dosing units that have the ability to effect the slow and positive supply of metallic additives, including platinum and/or cerium containing catalyst compositions, to fuel. The invention provides additive dosing materials and methods for simply and effectively supplying catalytic metal fuel additives to fuel in suitable low concentrations as are effective. The dosing units can be used with devices made to contact diesel fuel. In one approach, a catalytic metal additive concentrate (CMAC) is prepared in normally solid, semisolid or viscous form. The CMAC will preferably be encapsulated with a solid polymer. The encapsulation can be accomplished by embedding or dispersing the CMAC in a suitable polymer. If desired, the CMAC can be dispersed in one polymer and then the resulting composite can be embedded in the same or a different polymer. In an alternative form, a dosing unit can comprise a semisolid CMAC, which could be similarly held in contact with flowing fuel.

PRIORITY CLAIM

[0001] This application claims priority to prior U.S. Provisional Patent Application S. No. 60/366,860, filed Mar. 22, 2002.

BACKGROUND OF THE INVENTION

[0002] The invention concerns a new process for improving the delivery of metallic combustion catalysts to internal combustion engines and other combustion devices and to enable the production of additive delivery means which have the ability to effect the slow and positive supply of metallic additives, including platinum containing catalyst compositions, to fuel. The also invention provides additive release materials and methods designed for compatibility with various on-board delivery mechanisms.

[0003] A number of approaches have been utilized to deliver fuel additives to combustors such as internal combustion engines. Some additive delivery means require the use of highly concentrated catalyst mixtures with low volatility or high viscosity solvent carriers. Platinum and other catalyst metal components are not freely soluble or fully stable in forms compatible with some mechanisms used to achieve their slow release into fuels due to poor solubility in heavy solvents.

[0004] In U.S. Pat. No. 4,662,327, Sprugel, et al., disclose metering a liquid additive continuously into a fuel supply line. This liquid type delivery device has been viewed as complex and possessed of other disadvantages, leading to the development of devices based on solid, soluble additive materials.

[0005] In another system, Davis discloses a dissolvable element in U.S. Pat. No. 5,507,942. He provides a fuel filter assembly including a fuel additive element formed into a hollow cylindrical dissolvable insert comprising fuel additive in a wax substrate. In a preferred form, the fuel additive comprises a microbiocide that is compatible with combustion systems and fuels and which is more soluble in fuel than water. The microbiocide is encapsulated in the wax substrate, which has a high melting point and a burning characteristic for proper release of the microbiocide without compromising exhaust gas emissions and without unduly releasing an excessive amount of fuel additive that may adversely affect engine and fuel components. The fuel additive may also comprise cetane improvers, antioxidants, stabilizers, combustion improvers and emission reducers. The wax substrate is fabricated from a paraffin, which is said to be a hydrocarbon mixture with clean burning characteristics. The insert is housed within the hollow cylinder of a fuel filter canister. It is supported in a vertical orientation and slowly releases the fuel additive upon dissolving the wax substrate.

[0006] In U.S. Pat. No. 6,238,554, to Martin, Jr., et al., a fuel filter is described including a fuel additive that can be released into fuel. The rate of release for the fuel is said to be controlled to a substantially constant rate to maintain a uniform level of fuel additive in the fuel. Fuel from a filter chamber migrates through a diffusion orifice into an inner chamber and contacts an additive tablet which can have an outer coating. Fuel diffuses through the coating to contact a fuel additive composition, which dissolves in the fuel to provide a fuel composition comprising the dissolved additive. The fuel composition diffuses back through the coating into the inner chamber where it mixes with fuel. The fuel additives can be liquid or solid, and two or more fuel additives can be combined and can be compounded with a suitable polymer. They can be either a solid or semisolid material in a form, such as tablet, to control the rate of release of the additive into the fuel. The fuel additive can further include a wide variety of binders, compounding agents and mold release agents. When the additive is provided in liquid form, it is preferably combined with a suitable agent to form a solid or semisolid material. The term fuel additive includes antioxidants, antiwear agents, cetane improvers, corrosion inhibitors, demulsifiers, detergents, dispersants, flow improvers, lubricity agents, and metal deactivators. In other embodiments, the fuel additive can be embedded within a solid matrix. The matrix can be either hydrocarbon soluble or hydrocarbon insoluble. If the matrix material is hydrocarbon insoluble, the fuel must be able to penetrate the matrix and contact the fuel additive. It is disclosed to be particularly advantageous to embed a liquid fuel additive in a solid matrix. This is said to provide one means of controlling the rate the additive is released into fuel.

[0007] In U.S. Pat. No. 5,591,330, Lefebvre describes an oil filter containing an oil-soluble thermoplastic additive material. The thermoplastic material contains oil oxidation and acidification arresting additives and is positioned in a casing between a particle filtering material and a felt pad. The thermoplastic material can be high molecular weight polypropylene in the form of rice-shaped pellets, or spaghetti-shaped strands. The additives comprise about 10-17 weight % of the thermoplastic material/additive combination, and as the thermoplastic material is dissolved by above ambient temperature oil, the additives are released. High molecular weight polypropylene is described as superior for use as the thermoplastic material compared with polyester polycarbonates, polyallomer, polyethylene, and polysulfone, and ethylene propylene polypropylene is said to be particularly desirable.

[0008] In U.S. Pat. No. 4,075,098, Paul, et al., describe an oil filter containing a body of an oil soluble, relatively solid polymer having oil additives compounded therein. They note that virtually any polymer with desired properties may be used in practice in their system such as ethylene-propylene copolymers ranging in molecular weight from 200,000 to 300,000; ethylene-ethylacrylate polymers ranging in molecular weight from 200,000 to 300,000; polypropylene oxide having a molecular weight of about 500,000; and ethylene-vinyl acetate copolymer ranging in molecular weight from 200,000 to 300,000. One polymer described as highly satisfactory is polyisobutylene ranging in molecular weight from approximately 60,000 to 135,000. Similarly, in U.S. Pat. No. 3,336,223, Kneeland describes an oil filter having a polymeric insert carrying oil additives. The additives are incorporated into the oil as the polymer slowly dissolves.

[0009] In U.S. Pat. No. 5,456,217, to Thunker, et al., a device is described for direct addition of solid additives, such as ferrocene, to fuels for internal combustion engines. A solid additive is held in a replaceable cartridge, which is located in a portion of the filling neck of a fuel tank. Fuel filled through the neck dissolves the additive into the fuel.

[0010] The art does not describe or enable the preparation of platinum and/or cerium based fuel additive dosing units that can be used to controllably release platinum and/or cerium combustion catalysts into fuel in very low amounts by dissolution or diffusion.

[0011] Accordingly, there is a present need for a practical method of making a solid dosing form of platinum and/or cerium and/or iron combustion catalyst, the resulting additive composition and practical system for dosing fuels using it.

SUMMARY OF THE INVENTION

[0012] The invention provides a new process addressing the above needs with a solid dosing form of metallic combustion catalysts for fuels for combustors such as turbines, boilers, furnaces, process heaters, heat recovery units, diesel engines, and the like, utilizing carbonaceous, e.g., fossil, fuels such as distillate, residual and gaseous fuels.

[0013] The invention provides, in one aspect, a material effective in preparing units for dosing small amounts of platinum and/or cerium into fuel by dissolution or diffusion according to the invention. In this aspect the invention provides a catalytic metal additive concentrate (herein referred to as a CMAC) in nominally solid, semi-solid or viscous form.

[0014] The invention also provides dosing units for simply and effectively supplying catalytic metal fuel additives to fuel in suitable low concentrations as are effective. The dosing units can be provided in suitable shapes, e.g., cylinders, cubes, spheres, or like shapes, to use with fuel filters, fuel/water separators or other devices made to contact diesel fuel as it is pumped to the engine or stored in the fuel tank or other part of the fuel system.

[0015] In one approach for preparing dosing units for dosing small amounts of platinum and/or cerium into fuel by dissolution or diffusion according to the invention, a catalytic metal additive concentrate (herein referred to as a CMAC) is prepared and encapsulated with a solid polymer. Variations on this approach utilize the CMAC in various physical states including solid, semisolid or even highly viscous form. The encapsulation can be accomplished by embedding or dispersing the CMAC in a suitable polymer. Suitable polymers will provide structural integrity at the temperatures to be encountered and will release effective concentrations of the catalyst into the fuel under conditions of contact with the fuel. If desired, the CMAC can be dispersed in one polymer and then the resulting composite can be embedded in the same or a different polymer.

[0016] In some cases, the CMAC can be embedded in the polymer by mixing it with a polymer powder, melting the polymer while mixed with the CMAC, and solidifying the mixed polymer and CMAC in a desired shape. The fuel solubility characteristics of the polymer are chosen to define and limit the rate of additive release. The dosing units prepared in accord with the invention can supply a practically consistent additive application in the low ppm range to the fuel.

[0017] A preferred physical form for the CMAC materials of the invention is in normally solid form. In one alternative form, a dosing unit can comprise a semisolid (viscous to the point of resisting flow under its own weight) CMAC, which could be similarly held in contact with flowing fuel. Also, the CMAC can be viscous and fully subject to flow and deformation at ambient temperatures. If desired, the additive application rate to the fuel can be controlled by a relatively high viscosity of the CMAC, which is maintained in very limited contact with fuel flow, e.g., in a by-pass region.

[0018] The processes for preparing these products and their use in additive dosing systems which causes dissolution of the catalyst dosing units, are also provided.

[0019] Many of the preferred aspects of the invention are described below. Equivalent compositions are contemplated.

DESCRIPTION OF THE INVENTION

[0020] The invention relates to a new process addressing the above needs by providing an improved method for preparing a dosing form of metallic combustion catalyst for fuels for combustors such as turbines, boilers, furnaces, process heaters, heat recovery units, diesel engines, and the like, utilizing carbonaceous, e.g., fossil, fuels such as distillate, residual and gaseous fuels.

[0021] In one aspect, a catalytic metal additive concentrate (herein referred to as a CMAC) is provided to aid in forming units for dosing small amounts of platinum and/or cerium into fuel by dissolution or diffusion. These dosing units enable simply and effectively supplying catalytic metal fuel additives to fuel in suitable low concentrations as are effective.

[0022] Preferably, dosing units for dosing small amounts of platinum and/or cerium into fuel by dissolution or diffusion according to the invention, can be prepared by encapsulating a CMAC with a suitable polymer. The CMAC can be in various physical states including solid, semisolid or even highly viscous form. The encapsulation can be accomplished by embedding or dispersing the CMAC in a suitable polymer. Suitable polymers will preferably provide structural integrity at the temperatures to be encountered and will release effective concentrations of the catalyst into the fuel under conditions of contact with the fuel. In some cases, simply wrapping the CMAC with a polymer film will be effective. If desired, the CMAC can be dispersed in one polymer and then the resulting composite can be embedded in the same or a different polymer.

[0023] In some cases, the CMAC can be embedded in the polymer by mixing it with a polymer powder, melting the polymer while mixed with the CMAC, and solidifying the mixed polymer and CMAC in a desired shape. The fuel solubility characteristics of the polymer would be chosen to define and limit the rate of additive release. The dosing units prepared in accord with the invention can supply a reasonably consistent additive application in the low ppm range to the fuel.

[0024] A preferred physical form for the CMAC materials of the invention is in normally solid form. In one alternative form, a dosing unit can comprise a semisolid (viscous to the point of resisting flow under its own weight) CMAC, which could be similarly held in contact with flowing fuel. Also, the CMAC can be viscous and fully subject to flow and deformation at ambient temperatures. If desired, the additive application rate to the fuel can be controlled by a relatively high viscosity of the CMAC, which can be maintained in very limited contact with fuel flow, e.g., in a by-pass region.

[0025] The dosing units supply catalytic metal fuel additives to fuel in suitable low concentrations as are effective. The dosing units can be provided in suitable shapes, e.g., cylinders, cubes, spheres, saddles or like shapes, to use with fuel filters, fuel/water separators or other devices made to contact diesel fuel as it is pumped to the engine or stored in the fuel tank or other part of the fuel system or special dosing apparatus.

[0026] In one approach for preparing dosing units for dosing small amounts of platinum and/or cerium into fuel by dissolution or diffusion according to the invention, a CMAC is prepared in normally solid form and encapsulated with a solid polymer. By the tern “normally solid” as used herein we mean that preferred materials will be solid at temperatures of 50° C. and higher in that a one inch cube of material will substantially sustain its shape under its own weight at 20° C. for a the period of at least 60 minutes. Encapsulation can be accomplished by embedding or dispersing the CMAC in a suitable polymer. Suitable polymers will provide structural integrity at the temperatures to be encountered and will release effective concentrations of the catalyst into the fuel under conditions of contact with the fuel. If desired, the CMAC can be dispersed in one polymer and then the resulting composite can be embedded in the same or a different polymer.

[0027] In some cases the CMAC can be embedded in the polymer by mixing it with a polymer powder, melting the polymer, allowing the mixture to solidify in a desired shape. The fuel solubility characteristics of the polymer would be chosen to define and limit the rate of additive release. The dosing units prepared in accord with the invention can supply a reasonably consistent additive application in the low ppm range (e.g., concentrations of <20 ppm) to the fuel.

[0028] In an alternative form, a dosing unit can comprise a semisolid (viscous to the point of resisting flow under its own weight) CMAC, which could be similarly held in contact with flowing fuel. Here, the additive fuel dosing rate would be controlled by a relatively high viscosity of the CMAC in very limited contact with fuel flow in a by-pass region.

[0029] Normally-encountered solvents for additive components such as toluene, light mineral spirits and kerosene have too low a boiling point for normally solid CMAC containing dosing units. Moreover, they have too low a viscosity for the semisolid CMAC containing dosing units. Importantly, they will enable too low metal solubility for good application of either the solid or semisolid CMAC's. These normal solvents can prevent the formation of suitably high additive concentrations, as they exhibit solubility limits, especially for suitable platinum compounds, that are quite low. Some of these conventional solvents have the ability to dissolve only a few tenths of a percent of an active metal containing composition. This is true even of toluene, which is an especially good solvent. The mere addition of solid platinum compound to either a solid or semisolid CMAC, will result in a composition that is unstable and which will not deliver fuel borne catalyst (FBC) in uniform concentrations to the combustor and downstream components, resulting in erratic performance of the additive due to a highly fluctuating metal (especially Pt) concentration in the fuel.

[0030] In addition to these problems, decomposition points of the most soluble forms of platinum are too low to allow the use of some of the most favored polymers in the preparation of solid CMAC's. In this regard, it is noted that platinum COD (also referred to herein as “COD-Pt-diphenyl”), i.e., 1,5-cyclooctadiene platinum diphenyl, described in U.S. Pat. No. 4,891,050 to Bowers, et al., U.S. Pat. No. 5,034,020 to Epperly, et al., and U.S. Pat. No. 5,266,093 to Peter-Hoblyn, et al., decomposes at about 200° F. The disclosures of these patents are hereby incorporated by reference. Thus, dispersing COD-Pt-diphenyl in one preferred polymer melting at 150-200° C. (say, 350° F. or so) would result in destruction of the Pt complex with the resultant formation of platinum metal. This would also result in a highly nonuniform application of platinum to the system.

[0031] Not all fuel-soluble platinum materials decompose under these conditions, but their use can still present severe practical problems. Platinum acetylacetonate has a decomposition temperature of over 200° C.; however, it has very poor solubility in any solvent, only being about 0.5% soluble even in toluene and correspondingly less soluble in higher aromatic solvents. It is almost insoluble in aliphatics such as mineral spirits. Other suitable platinum compounds exhibit similar problems.

[0032] In one aspect, the invention provides a method of preparing a solid dosing form of fuel additive, by: preparing a stable dispersion of platinum compound in a predetermined catalyst (e.g., a suitable Pt/Ce ratio) ratio in a solution of cerium (or other catalyst compound, such as one based on iron) soap, mixing the dispersion with a fuel-soluble polymer under conditions effective to uniformly distribute the dispersion within the polymer; and forming the polymer into a predetermined shape.

[0033] The noted stable dispersion of platinum compound ha a predetermined Pt/Ce ratio in a solution of cerium soap (or other catalysts), can be prepared by adding a designated platinum compound as a solid or otherwise to the cerium soap solution and milling in a ball mill or other suitable particle mill to reduce the solids to small particles that permit the formation of a stable dispersion. The soaps present in the cerium soap solution disperse the solid platinum compound particles and prevent agglomeration and subsequent loss of stability. Additional dispersant, can be added if necessary. There are many of these known to the art but one of the most suitable is oleic acid. Others include amphoterics such as oleyl imidazolines and the like. Where the amounts of oleates in the catalyst metal concentrates are high enough, Such additions are not necessary.

[0034] This procedure results in a stable or semi-stable dispersion without further processing. However, solvent evaporation will accomplish at least two further goals: to further concentrate the additive package and increase the viscosity of the resulting solution to levels where complete dispersion stability is achieved. This also removes the low boiling solvents that can be troublesome. Solvent evaporation, in combination with suitable processing, can result in a final additive concentrate that is up to about 50% cerium and 1% or more platinum (both as metal basis) ha a liquid, usable form. These are very high concentrations for catalyst metals of the type concerned.

[0035] The noted stable dispersions can also be formed by adding a platinum compound to the soap as a solution, usually in a light carrier such as toluene, and evaporating the light carrier along, with the light components ha the solvent evaporation step. This results in the precipitation of small particles of solid platinum compound dispersed in the cerium soap solution. These can then be milled or not depending on the degree of stability required.

[0036] In another aspect, the invention provides a method of preparing, a solid dosing form of fuel additive, by: preparing a solution of a platinum composition including a typical low-boiling solvent including a sufficient amount of high-boiling solvent to retain fluidity of the composition in the absence of the low-boiling solvent; evaporating the low-boiling solvent to prepare a viscous catalyst solution; mixing the viscous catalyst solution with a fuel-soluble polymer under conditions effective to uniformly distribute the dispersion within the polymer; and forming the polymer into a predetermined shape.

[0037] In this case, mineral oil and other high boiling aliphatics are preferred because the normal platinum compounds are poorly soluble in them. The use of more soluble solvent systems would actually be detrimental as these promote crystal growth and dissolution of the solid dispersed phase, resulting in degradation of the dispersion. Inorganic forms of platinum could also be used, but the resulting cake or liquid would release a stream of fine particles of platinum compound rather than dissolved forms. This will be acceptable if the particle size is small enough to prevent settling out in other parts of the system, filter plugging and injector failure. Accordingly, extremely small, highly milled dispersed particles of platinum oxide or similar compounds are contemplated.

[0038] The polymer used to mix with the platinum and other catalyst dispersion or solution as noted above, will be one of those, such as from the patents cited above, which is soluble in the fuel at a degree sufficient to release the additive to the fuel. Polymers based on olefins, e.g., polyethylene, polypropylene, and copolymers of ethylene and propylene, can be used with good effect. In embodiments where a solvent is used to dissolve the catalyst composition for mixing with a polymer for processing in melt form, both the catalyst composition and the solvent have properties which assure their survival in a suitable form. Catalysts are described below. Solvents of the hydrocarbon type are suitable where they are either of suitably high boiling point initially or evaporated to be freed of low boiling components. Preferred boiling points for solvents will be over 100° C., and preferably over 150° C. Specific examples are given below.

[0039] The polymer and the CMAC can be blended at any suitable ratio to give the desired release rate when placed in contact with the fuel under the conditions of operation. Typically, ratios of CMAC to polymer should be at a ratio of from about 3:1 to about 1:100, typically from about 1:1 to about 1:10. The concentration of metal within the blend will desirably be within the range of from about 10 to about 600 mg metal to gram of blend, more narrowly from about 300 to about 500 mg metal to gram of blend. One test of the suitability of the blend is to place a 1 cm³ cube of the blend in 1 liter of fuel for 1 hour and measure the concentration of metal in the fuel. The preferred blends of polymer and CMAC materials will equilibrate at levels within the desired dosage rates given below.

[0040] The blends of polymer and CMAC materials are shaped typically by heating, e.g., at an elevated temperature of from about 150° C. to about 300° C., and molding. Preferred polymers will melt or soften at temperatures within this range. Typically, a mixture of polymer with a CMAC is shaped by a suitable molding or other forming technique, e.g., compression molding, injection molding, extrusion, or the like. If desired, for some applications, the blends of polymer and CMAC materials can be enveloped in a suitable polymer film which can be permeated by the fuel and permit leaching into the fuel at a controlled rate. Typical of the films are ABS, polyalkenes, polyalcohols like polyvinyl alcohol, polyesters like polyvinyl acetate, and other polymers having similar permeabilities or which can be formed with similar permeabilities for the fuel in question. The preferred polymers include those that can be applied by dipping, coextrusion or simple lamination techniques.

[0041] As required by a particular process or combustor, any suitable fuel can be treated with a CMAC prepared in accord with the invention. It can be one or a blend of fuels selected from the group consisting of distillate fuels, including diesel fuel, e.g., No. 2 Diesel fuel, gasoline, jet fuel, e.g., Jet A, or the like, and biologically-derived fuels, such as those comprising a “mono-alkyl ester-based oxygenated fuel”, i.e., fatty acid esters, preferably methyl esters of fatty acids derived from triglycerides, e.g., soybean oil, Canola oil and/or tallow. Other hydrocarbons, including liquids and gases, e.g., natural gas, or fuels derived from gas and/or emulsion components can be employed.

[0042] Cerium and/or iron catalyst levels can be dosed into the fuels at fairly uniform levels to provide concentrations in the fuel of as low as 0.05 ppm and platinum levels can be as low as 0.0005 ppm.

[0043] The process of the invention employs a fuel-soluble, multi-metal catalyst, preferably comprising fuel-soluble platinum and either cerium or iron. The cerium or iron are typically dosed in amounts sufficient to provide concentrations in the fuel of from 0.5 to 25 ppm and the platinum from 0.0005 to 2 ppm, with preferred fuel concentrations of cerium and/or iron of from 5 to 10 ppm, e.g., 7.5 ppm, and the platinum from 0.05 to 0.5 ppm, e.g., 0.15 ppm. A preferred ratio of cerium and/or iron to platinum is from 75:1 to 10:1. One narrower range is from 60:1 to 25:1.

[0044] The fuel treated with a CMAC of the invention can contain detergent (e.g., 50-300 ppm), lubricity additive (e.g., 25 to about 500 ppm), other additives, and suitable fuel-soluble catalyst metal compositions, e.g., 0.1-2 ppm fuel soluble platinum group metal composition, e.g., platinum COD or platinum acetylacetonate and/or 2-20 ppm fuel soluble cerium or iron composition, e.g., cerium, cerium octoate, ferrocene, iron oleate, iron octoate and the like.

[0045] A combination of platinum with either iron or cerium at low concentrations in fuels is as effective as much higher concentrations of cerium, iron or other metals without platinum in reducing carbon or soot deposits or emissions. Concentrations of a few ppm metals in combination are as effective as 30-100 ppm of iron and/or cerium used alone. The metal concentration in the fuel achieved by using the CMAC formulations of the invention avoid problems often encountered using traditional levels of cerium or iron, which are high enough to be factors in causing equipment fouling due to the high ash burden associated with high metal concentrations in the fuel.

[0046] The preferred bimetallic and trimetallic platinum and other catalyst metal combinations are compatible with standard additive components for distillate and residual fuels such as pour point reducers, antioxidant, corrosion inhibitors and the like.

[0047] Among the specific cerium compounds are: cerium III acetylacetonate, cerium III napthenate, and cerium octoate, cerium oleate and other soaps such as stearate, neodecanoate, and octoate (2-ethylhexoate). Many of the cerium compounds are trivalent compounds meeting the formula: Ce (OOCR)₃ wherein R=hydrocarbon, preferably C₂ to C₂₂, and including aliphatic, alicyclic, aryl and alkylaryl. The cerium is preferred at concentrations of 1 to 15 ppm cerium w/v of fuel. Fatty acid containing compounds of this type are known to the art as soaps. Preferably, the cerium is supplied as cerium hydroxy oleate propionate complex (diluted with light mineral spirits to 40% cerium by weight). Preferred levels are toward the lower end of this range, e.g., less than 8 ppm.

[0048] Among the specific iron compounds are: ferrocene, ferric and ferrous acetylacetonates, iron soaps like octoate and stearate (commercially available as Fe(III) compounds, usually), iron pentacarbonyl Fe(CO)₅, iron napthenate, and iron tallate.

[0049] Any of the platinum group metal compositions, e.g., 1,5-cyclooctadiene platinum diphenyl (platinum COD, also referred to as “COD-Pt-diphenyl”), described in U.S. Pat. No. 4,891,050 to Bowers, et al., U.S. Pat. No. 5,034,020 to Epperly, et al., and U.S. Pat. No. 5,266,093 to Peter-Hoblyn, et al., can be employed as the platinum source. Other suitable platinum group metal catalyst compositions include commercially-available or easily-synthesized platinum group metal acetylacetonates, platinum group metal dibenzylidene acetonates, and fatty acid soaps of tetramine platinum metal complexes, e.g., tetramine platinum oleate.

[0050] The combustion of a fuel treated according to the invention can be of an emulsion with water, wherein an oil phase is emulsified with water, the water comprising from 1 to 30% water based on the weight of the distillate fuel, residual fuel, aviation kerosene or the like. In the preferred forms, the emulsion will be predominantly of the water-in-oil type and will preferably contain surfactants, lubricity additives and/or corrosion inhibitors in addition to the other components mentioned above. A discussion of suitable emulsion forms and additives is found in U.S. Pat. No. 5,743,922. The additives introduced into, the fuel in accord with the invention can improve combustion efficiency and reduce particulates without the use of oxidation catalysts or particulate filters for enhanced emissions control on diesel engines. Also, better carbon burn out in open flame combustion sources will lead to lower carbon deposits on heat transfer surfaces and lower soot oxidation temperatures on downstream heat recovery devices.

[0051] The invention will be better understood when the above description is read in light of the following non-limiting examples, wherein all parts and percentages are given by weight, unless otherwise specifically indicated to the contrary.

EXAMPLE 1

[0052] This example describes the preparation of a solid CMAC according to the invention containing a cerium catalyst composition. Two hundred grains of cerium hydroxy oleate propionate complex (diluted with light mineral spirits to 40% cerium by weight), was mixed with 40 grams of heavy mineral oil and charged into a 500 ml vacuum distillation apparatus. The flask was immersed in an oil bath with temperature control. Vacuum was applied using a water eductor mechanism and the oil bath temperature slowly increased. After about an hour, the temperature reached 125° C. and the distillation was stopped, the flask was reweighed and the resulting weight after processing indicated that 50.46 grains of solvent had distilled over to the receiver. The resulting concentrate was calculated to have a cerium metal concentration of 42% by weight. A small beaker of material produced was heated on a hot plate and the boiling point was found to be over 175° C. and suitable for processing temperatures encountered with polymers of the type employed in the invention to provide slow release fuel additive substrates.

EXAMPLE 2

[0053] A solid CMAC produced in Example 1, above, is mixed to form a uniform blend with a powder of ethylene-propylene polymer (MP=150° C.) at a weight ratio of 50:50 and heated to 175° C. in i compression mold to form a slow release fuel additive insert in the form of a cylinder to be inserted in a suitable holder for placement in a fuel passage chamber.

EXAMPLE 3

[0054] This example describes the preparation of a solid CMAC according to the invention containing both platinum and cerium catalyst compositions at a 50:1 weight ratio of cerium to platinum. To 200 grains of cerium hydroxy oleate propionate complex (diluted with light mineral spirits to 40% cerium) is added 3.2 grams of solid platinum acetylacetonate and the materials are ball milled overnight, to produce a semi-stable dispersion of platinum acetylacetonate in the cerium concentrate. The resulting mixture is then further mixed with 40 grams of heavy mineral oil and charged into a 500 ml vacuum distillation apparatus. The flask is immersed in an oil bath with temperature control and vacuum is applied using, a water eductor mechanism and the oil bath temperature slowly increased. Processing is completed as in Example 1.

EXAMPLE 4

[0055] This example describes the preparation of a CMAC according to the invention containing both platinum and cerium catalyst compositions at a 50:1 weight ratio of cerium to platinum. In this case, 310 grains of 40% cerium concentrate was charged to a 1-liter ball mill with ceramic media. Then, 5.0 grams of platinum acetylacetonate was added to the mill and the mill sealed. The mixture was ball milled overnight, producing a semi-stable dispersion of platinum acetylacetonate in the cerium concentrate. The resultant mixture slowly (over an hour or two) deposited a small amount of solid platinum compound on the bottom of the container. A total of 288.7 grains was recovered from the ball mill and transferred to a 500 ml round bottom flask. To this, 3.0 grams oleic acid and 68 grains heavy mineral oil were added to the cerium+platinum mixture in the flask and mixed. This was vacuum distilled as in the previous examples under water eductor vacuum to an end temperature of 130° C. and allowed to cool. Analysis showed that 76.0 grams of light solvents had been removed by the distillation process leaving 283.7 grams of a viscous product containing 0.80% platinum and 40.1% cerium. The resultant final product was found to be completely soluble in hydrocarbon solvents. This product was suitable for blending with polymer powder at 175° C. to form an additive wafer that would supply fuel soluble forms of platinum and cerium in a controlled manner.

EXAMPLE 5

[0056] This example repeats the procedure of Example 4, but employs added oleic acid as a dispersant in replacement for the heavy mineral oil. Processing is otherwise essentially the same.

EXAMPLE 6

[0057] This example describes the preparation of another CMAC according to the invention containing cerium catalyst composition. Two hundred grams of 40% cerium concentrate was mixed with 60 grains of heavy mineral oil and charged into a 500 ml vacuum distillation apparatus. The flask was immersed in an oil bath with temperature control. Vacuum was applied using a water eductor mechanism and the oil bath temperature slowly increased. After 90 minutes, the temperature reached 160° C. and the distillation was stopped, the flask was reweighed and the resulting weight indicated that 54.84 grams of solvent had distilled over to the receiver. The resulting concentrate was calculated to have a cerium metal concentration of 39% wt. The result of this process was suitable for processing temperatures of 175° C. with high melting polymers and had a lower viscosity than Example 1, making it easier to work into a polymer powder.

EXAMPLE 7

[0058] This example describes the preparation of a semisolid CMAC according to the invention containing both platinum and cerium catalyst compositions at a 50:1 weight ratio of cerium to platinum. In this procedure, platinum compound solutions in suitable solvents are added to a mixture of cerium catalyst material and solvents (as in Example 4) in the distillation apparatus. In particular, 80 grams of Platinum Plus 3100-SC, a 4.7% solution of COD-Pt-diphenyl in toluene, are added. The final processing temperatures is maintained below 100° C. to avoid the decomposition into platinum metal in the matrix.

EXAMPLE 8

[0059] This example describes the preparation of a semisolid CMAC according to the invention as set out in Example 7, but employs platinum acetylacetonate in place of the COD-Pt-diphenyl, and the temperature is maintained at less than 250° C.

EXAMPLE 9

[0060] The procedure of Example 7 is repeated but this time the ratio of platinum:cerium is 1:15, obtained by increasing the amount of platinum compound in the composition proportionately.

EXAMPLE 10

[0061] This example describes the preparation of another CMAC according to the invention containing cerium catalyst composition. Two hundred grams of 40% cerium concentrate was mixed with 100 grains of heavy mineral oil and charged into a 500 ml vacuum distillation apparatus. The flask was immersed in an oil bath with temperature control. Vacuum was applied using a water eductor mechanism and the oil bath temperature slowly increased. After 90 minutes, the temperature reached 160° C. and the distillation was stopped, the flask was reweighed and the resulting weight indicated that about 55 grams of solvent had distilled over to the receiver. The resulting concentrate was calculated to have a cerium metal concentration of 32% wt. The result of this process was suitable for processing temperatures of 175° C. with high melting polymers and had a lower viscosity than Example 1, making it easier to work into a polymer powder.

[0062] The above description is intended to enable the person skilled in the art to practice the invention. It is not intended to detail all of the possible modifications and variations which will become apparent to the skilled worker upon reading the description. It is intended, however, that all such modifications and variations be included within the scope of the invention which is seen in the above description and otherwise defined by the following claims. The claims are meant to cover the indicated elements and steps in any arrangement or sequence which is effective to meet the objectives intended for the invention, unless the context specifically indicates the contrary. 

1. A high temperature stable platinum and/or cerium fuel additive dosing unit, comprising: (a) catalytic metal additive concentrate comprising fuel soluble platinum and/or cerium composition stable at temperatures above 100° C., uniformly dispersed in an organic carrier in relative quantities to be normally solid; (b) encapsulated with a solid polymer as an infusion control composition.
 2. A high temperature stable platinum and/or cerium fuel additive dosing unit according to claim 1, wherein the catalytic metal additive concentrate is embedded in the polymer.
 3. A high temperature stable platinum and/or cerium fuel additive dosing unit according to either of claims 1 or 2, wherein the catalytic metal additive concentrate is uniformly dispersed within the polymer.
 4. A high temperature stable platinum and/or cerium fuel additive dosing unit according to any of claims 1, 2 or 3, wherein the catalytic metal additive concentrate comprises platinum acetylacetoneate.
 5. A high temperature stable platinum and/or cerium fuel additive dosing unit according to any of claims 1, 2, 3 or 4, wherein the catalytic metal additive concentrate comprises a cerium soap.
 6. A method of preparing a solid dosing form of fuel additive, by: preparing a stable dispersion of platinum composition in a predetermined Pt/Ce ratio in a solution of cerium soap; encapsulating the viscous catalytic metal additive concentrate comprising fuel soluble platinum and/or cerium composition stable at temperatures above 100° C. with a infusion controlling polymer.
 7. A method according to claim 6, wherein the viscous catalytic metal additive concentrate is encapsulated by embedding it in an infusion control polymer.
 8. A method according to claim 6, including the further steps of: mixing the dispersion of platinum composition and cerium soap with an infusion control polymer under conditions effective to uniformly distribute the dispersion within the polymer; and forming the resulting mixture of polymer into a dosing unit of predetermined shape.
 9. A method according to claim 7, including the further step of: embedding the dosing unit in an infusion control polymer.
 10. A method of preparing a solid dosing form of fuel additive, by: preparing a solution of a platinum and/or cerium composition including a low-boiling solvent including a sufficient amount of high-boiling solvent to retain fluidity of the composition in the absence of the low-boiling solvent; evaporating the low-boiling solvent to prepare a viscous catalytic metal additive concentrate comprising fuel soluble platinum and/or cerium composition stable at temperatures above 100° C.; encapsulating the viscous catalytic metal additive concentrate comprising fuel soluble platinum and/or cerium composition stable at temperatures above 100° C. with a infusion controlling polymer.
 11. A method of using a solid dosing form of fuel additive, comprising: obtaining a solid dosing form of catalyst according to any of the preceding claims; and contacting the solid dosing form of catalyst with fuel to partially dissolve the polymer and introduce the catalyst into the fuel prior to combustion.
 12. A method of forming a catalytic metal additive concentrate, comprising: forming a mixture of a catalytic metal soap and a solvent; removing low-boiling solvent.
 13. A method according to claim 12, wherein high boiling solvent is added prior to removing low boiling solvent.
 14. A method according to claim 12, wherein the catalytic metal soap comprises a cerium soap.
 15. A method according to claim 14, wherein the catalytic metal further comprises platinum acetylacetonate.
 16. A method according to claim 14, wherein the catalytic metal further comprises COD-Pt-diphenyl. 